According to mapquest
Chambers Bay is 140 miles north of Portland.
Portland to Chambers Bay to Bandon is 9.5 hours
Portland to Astoria to Bandon is 8 hours
You only tack on an hour and a half to go play Chambers Bay and most of the driving will be interstate vs. all of it being two lane hiway. You might as well take in Chambers Bay instead of Astoria.